With the continuous development of the radio communication industry, more and more users choose to use radio communication; the current radio communication is not limited to voice communication, while wider data service communication is especially a direction for the development of the radio communication system, for example, video, business or commercial data and the like. With the gradually enlarged radio communication scale, the lack of radio spectrum resource is highlighted. Current spectrum allocation system usually refers to fixed allocation, namely allocating fixed spectrum resources for authorized users, this further intensifies the tight situation of the spectrum resources. For example, the authorized users do not always occupy the allocated spectrum in accordance with a lot of actually observed results in a world wide, namely a part of spectrum is always idle on certain time, space and frequency band and no matter adopting what kind of radio accessing technologies. This provides possibilities for effectively utilizing the idle spectrum resources and providing paid services for non-authorized users, so that the utilization of the spectrum is improved and the pressure of the spectrum resource is reduced. Cognitive Radio (CR) technology is developed under the background.
When the cognitive system is required to perform handover (HO) due to demand of service, for example the demand of transmission of video or large-scale commercial data, or change of signal channel quality, the existing method has the problems of slow handover speed, easy disconnection and the like. The main reasons of above problems are as follows: slow spectrum sensing, when the system is required to handover and no new spectrum resource is sensed, the handover speed is slow; when the system is handed over, the coordination of equipment such as terminal, base station, gateway and the like (including software, hardware and signaling) goes wrong thereby causing disconnection.
How to perform the handover fast and smoothly is a problem urgently needed to solve.